1926 £1 pale olive-green & red, Setting VIa, 9½mm between, "South West" 16½mm long (SG 40a/CC 63a). PLATE NO1 CONTROL BLOCK OF FOUR, Superb fresh UM from bottom right corner. Lightest prior hinge trace margins only, minimal suggestion diagonal gum wrinkle as usually found for these. Perf reinforced top right. A most elusive plate block, few of the possible 100 control pairs ever existing (from the only 25 sheets printed, ie only 25 possible each corner) survive. (cvR175000+). See additional image.
